#ifdef DEBUG
    prt("DEBUG En.PdV     =%16.6f",En.PdV);
    prt("DEBUG PdVkin     =%16.6f",Pkin);
    prt("DEBUG dVvir      =%16.6f",vir);
    prt("DEBUG PdVvir     =%16.6f",vir/box.V);
#endif /*# DEBUG */
